1. Field of the Invention
This invention relates to a detachable introducer for inserting a medical device deployment system into the vasculature of a human body and further relates to a method of using such introducer. The deployment system may be used for placing a medical device at a preselected position within a vessel. More particularly, the introducer is suited for inserting an embolic coil deployment system into the tortuous vasculature of the human brain for placing an embolic coil within an aneurysm.
2. Description of the Prior Art
For many years physicians have been placing various devices within a blood vessel of the human body in order to treat an aneurysm or to occlude a vessel. These devices are placed within the aneurysm or vessel using one of several different catheter deployment systems. These deployment systems transport and release the devices at a particular location within the vessel. The combination of different devices and different deployment systems provide physicians with reliable methods of treating aneurysms.
Physicians place various types of devices within an aneurysm or a vessel to occlude the flow of blood by promoting thrombus formation. Such devices include dilatation balloons, liquid medications, and embolic coils. Embolic coils may take the form of helically wound coils, randomly wound coils, coils wound within other coils, and many other coil configurations. These coils are generally formed of radiopaque metallic materials, such as platinum, gold, and tungsten, or alloys of these metals. Often times, several coils are placed at a given location in order to occlude the flow of blood through the vessel.
U.S. Pat. No. 6,179,857, entitled, “Stretch Resistant Embolic Coil With Variable Stiffness” discloses one example of such an embolic coil design. The coil disclosed in this patent is a helically wound coil, and various combinations of adjacent turns are spot welded together to create a stretch resistant coil of varying flexibility. U.S. Pat. No. 6,183,491, entitled, “Embolic Coil Deployment System With Improved Embolic Coil” discloses another embolic coil configuration which has a relatively flexible proximal portion which resists stretching.
Also, U.S. Pat. No. 5,853,418, entitled “Stretch Resistant Vaso-occlusive Coils,” discloses a helically wound coil having a polymeric stretch resistant member extending through the lumen of the coil and fixedly attached to both the distal end and the proximal end of the coil. Other examples of coil configurations are disclosed in U.S. Pat. No. 5,334,210, entitled, “Vascular Occlusion Assembly” and U.S. Pat. No. 5,382,259 entitled, “Vasoocclusion Coil With Attached Tubular Woven Or Braided Fibrous Covering.” With all such coil designs, it is important that the coils remain very flexible so that they may be passed through vessels with the use of a catheter deployment system.
A variety of coil deployment systems are available for placing embolic coils within an aneurysm or vessel. U.S. Pat. No. 6,113,622, entitled, “Embolic Coil Hydraulic Deployment System” and assigned to the same assignee as the present patent application discloses one example of such a deployment system. The hydraulic embolic coil deployment system disclosed in this patent uses fluid pressure which is applied to the lumen of the deployment catheter for expanding the distal section radially thereby releasing the embolic coil at a preselected position.
U.S. Pat. No. 5,350,397, entitled, “Axially Detachable Embolic Coil Assembly” discloses another known coil deployment system which utilizes a deployment catheter having a socket at the distal end for retaining a ball which is bonded to the proximal end of the embolic coil. The ball is placed within the socket at the distal end of the deployment catheter, and the deployment system is then moved into a vessel to place the coil at a desired position. A pusher wire with a piston at its distal end is pushed distally from the proximal end of the deployment catheter to thereby push the ball out of the socket and release the coil at the desired position.
Also, U.S. Pat. No. 5,263,964, entitled, “Coaxial Traction Detachment Apparatus and Method” discloses still another coil deployment system. The system disclosed in this patent uses glue or solder for attaching an embolic coil to a guidewire which is, in turn, pushed through a flexible catheter for positioning the coil within the vessel at a preselected position. Once the coil is at the desired position, the coil is restrained by the deployment catheter, and the guidewire is pulled from the proximal end of the coil causing the coil to become detached from the guidewire and released from the deployment system.
Additionally, U.S. patent application Ser. No. 09/580,684 entitled, “Small Diameter Embolic Coil Hydraulic Deployment System,” filed on May 30, 2000 and assigned to the same assignee as the present patent application, discloses a vasoocclusive coil deployment system for placing a small diameter coil. In the system disclosed in this patent, the distal end of a cylindrical headpiece is inserted into and bonded to the embolic coil. The proximal end of the cylindrical headpiece has a diameter approximately equal to the diameter of the lumen of a deployment catheter so that the cylindrical headpiece is disposed in fluid-tight engagement with the lumen of the deployment catheter. When fluid pressure is applied to the lumen of the deployment catheter, the outer wall of the distal section of the deployment catheter expands radially and releases the cylindrical headpiece along with the embolic coil.
Examples of other such coil deployment systems are disclosed in U.S. Pat. No. 5,122,136, entitled, “Endovascular Electrolytically Detachable Guidewire Tip For The Electroformation Of Thrombus In Arteries, Veins, Aneurysms, Vascular Malformations And Arteriovenous Fistulas” and U.S. Pat. No. 5,108,407, entitled, “Method And Apparatus For Placement Of An Embolic Coil.”